The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingSteering angle sensor
Components
Removal
Precaution
Caution:
Be sure to read the "precaution" thoroughly
before servicing (see page rs-1).
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery termin ...
Air conditioning amplifier communication stop mode
Description
Wiring diagram
Inspection procedure
Notice:
Turn the ignition switch off before measuring the resistances
of the main wire and the branch
wire.
After the ignition switch is turned off, check that the key
reminder warning system and light
reminder warning sy ...
Headlight dimmer switch
Precaution
Precaution for vehicle with srs
Some procedures in this section may affect the
supplemental restraint system (srs). Prior to
performing the procedures, read the srs section's
"precaution" (see page rs-1).
Components
Removal
Disconnect cable from negat ...